It is known in the semiconductor arts to fabricate inductors using thin film structures. Metal thin film inductors generally are formed in spiral or rectangular snake patterns across a surface of a semiconductor substrate.
Conventional spiral inductors have many problems. One of the features inherent in an integrated circuit having an inductor is the need for large areas or volumes in order to produce acceptable inductance values. The inductance value (Q) which can be achieved by a given inductor is a function of its length and the number of turns or coils which can be fabricated in the structure. Horizontal inductors become large very rapidly as the length and number of turns increases, and thus large inductance values cannot be achieved using horizontal or planar structures. Furthermore, existing planar embedded inductors suffer from low Q values, high series resistance, substrate coupling, and deleterious resonant contributions from cladding and/or barrier layers in damascene interconnections.
Accordingly, a need exists for an inductor with minimal horizontal surface area and a high inductance, which can be manufactured using conventional methods.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “comprise,” “include,” “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. The term “coupled,” as used herein, is defined as directly or indirectly coupled in an electrical or non-electrical manner.